Combating a resurgence of poliomyelitis through public health surveillance and vaccination

Poliomyelitis, or polio, is a highly infectious disease and can result in permanent flaccid paralysis of the limbs. Singapore was certified polio-free by the World Health Organization (WHO) on 29 October 2000, together with 36 other countries in the Western Pacific Region. The last imported case of polio in Singapore was in 2006. Fortunately, polio is vaccine-preventable-the world saw the global eradication of wild poliovirus types 2 and 3 achieved in 2015 and 2019, respectively. However, in late 2022, a resurgence of paralytic polio cases from vaccine-derived poliovirus (VDPV) was detected in countries like Israel and the US (specifically, New York); VDPV was also detected during routine sewage water surveillance with no paralysis cases in London, UK. Without global eradication, there is a risk of re-infection from importation and spread of wild poliovirus or VDPV, or new emergence and circulation of VDPV. During the COVID-19 pandemic, worldwide routine childhood vaccination coverage fell by 5% to 81% in 2020-2021. Fortunately, Singapore has maintained a constantly high vaccination coverage of 96% among 1-year-old children as recorded in 2021. All countries must ensure high poliovirus vaccination coverage in their population to eradicate poliovirus globally, and appropriate interventions must be taken to rectify this if the coverage falters. In 2020, WHO approved the emergency use listing of a novel oral polio vaccine type 2 for countries experiencing circulating VDPV type 2 outbreaks. Environmental and wastewater surveillance should be implemented to allow early detection of "silent" poliovirus transmission in the population, instead of relying on clinical surveillance of acute flaccid paralysis based on case definition alone.

Enteric Fever in a Tertiary Paediatric Hospital: A Retrospective Six-Year Review

<p><b>INTRODUCTION</b>Enteric fever is a multisystemic infection which largely affects children. This study aimed to analyse the epidemiology, clinical presentation, treatment and outcome of paediatric enteric fever in Singapore.</p><p><b>MATERIALS AND METHODS</b>A retrospective review of children diagnosed with enteric fever in a tertiary paediatric hospital in Singapore was conducted from January 2006 to January 2012. Patients with positive blood cultures for Salmonella typhi or paratyphi were identified from the microbiology laboratory information system. Data was extracted from their case records.</p><p><b>RESULTS</b>Of 50 enteric fever cases, 86% were due to Salmonella typhi, with 16.3% being multidrug resistant (MDR) strains. Sixty-two percent of S. typhi isolates were of decreased ciprofloxacin susceptibility (DCS). Five cases were both MDR and DCS. The remaining 14% were Salmonella paratyphi A. There were only 3 indigenous cases. Ninety-four percent had travelled to typhoid-endemic countries, 70.2% to the Indian subcontinent and the rest to Indonesia and Malaysia. All patients infected with MDR strains had travelled to the Indian subcontinent. Anaemia was a significant finding in children with typhoid, as compared to paratyphoid fever (P = 0.04). Although all children were previously well, 14% suffered severe complications including shock, pericardial effusion and enterocolitis. None had typhoid vaccination prior to their travel to developing countries.</p><p><b>CONCLUSION</b>Enteric fever is largely an imported disease in Singapore and has contributed to significant morbidity in children. The use of typhoid vaccine, as well as education on food and water hygiene to children travelling to developing countries, needs to be emphasised.</p>

Risk Factors for Severe Adenovirus Infection in Children during an Outbreak in Singapore

<p><b>BACKGROUND</b>Human adenoviruses (HAdVs) can cause a variety of human illnesses, with associated temporal and geographic changes in disease incidence. We report the emergence of an outbreak of HAdV infections in Singapore, presumably caused by a change of the predominating type to HAdV-7. We examined the clinical features of children admitted with HAdV infection to 1 institution and the risk factors for severe infection.</p><p><b>MATERIALS AND METHODS</b>This is a retrospective case-control study of all HAdV-infected children admitted during weeks 1 to 19 in 2013, as identified from laboratory records. A descriptive retrospective analysis of epidemiology, clinical data and the outcome of these children was also performed. Patients with severe infections were defined as cases, those with non-severe infections as controls, and the 2 groups were compared to find possible independent risk factors.</p><p><b>RESULTS</b>Eighty-five patients with HAdV infection were studied, including 11 (12.9%) cases and 74 (87.1%) controls. Binary logistic regression showed that cases were more likely to be <2 years old (adjusted OR 10.6, 95% CI, 1.8 to 63.2) and to have significant comorbidities (adjusted OR 19.9, 95% CI, 3.4 to 116.1) compared to controls. The predominant type in 2013 was HAdV-7, which differed from 2011 and 2012, when HAdV-3 was more common. There was a trend towards pneumonia being more common in patients infected with HAdV-7 than in patients infected with other types, although this did not reach statistical significance (OR 2.8, 95% CI, 0.9 to 8.7).</p><p><b>CONCLUSION</b>The emergence of HAdV-7 in a population where other HAdV types had circulated previously may have caused the outbreak in Singapore, and this was associated with more serious infections in children. Young age (<2 years) and significant comorbidities were associated with more severe HAdV infection.</p>

Granulomatous cervicofacial lymphadenitis in children: a nine-year study in Singapore

<p><b>INTRODUCTION</b>Granulomatous cervicofacial lymphadenitis (GCL) is not uncommon in children. Nontuberculous mycobacteria (NTM) seem to be the predominant cause. We sought to study the clinical and microbiological profile of patients with GCL, and identify features that may impact outcome.</p><p><b>METHODS</b>Children aged < 16 years who presented to KK Women's and Children's Hospital, Singapore, between January 1998 and December 2006, and who had GCL were identified from laboratory records. Clinical and laboratory data was collected and analysed for risk factors for patients with positive lymph node cultures, and for patients with and without recurrence after treatment.</p><p><b>RESULTS</b>In all, 60 children were identified, with a median age of 56 (interquartile range [IQR] 34-101) months. Median duration of symptoms before presentation was 5 (IQR 4-8) weeks. The majority presented with single (73.3%) or unilateral (96.7%) lymphadenopathy, located in the submandibular, preauricular/parotid or infra-/post-auricular region (76.7%). Out of 51 patients, 26 (51.0%) had a tuberculin skin test reading of ≥ 10 mm. Out of 52 patients, 10 (19.2%) had positive mycobacterial cultures, which included seven isolates of NTM. Out of 34 cases, tuberculous polymerase chain reaction was positive in 11 (32.4%). With regard to recurrence after initial treatment, age < 5 years at presentation was found to be a predictor for recurrence (p = 0.008), while initial complete excision of affected nodes predicted no recurrence (p = 0.003).</p><p><b>CONCLUSION</b>In our study, younger age was noted to be associated with a higher chance of recurrence, while complete excision of the involved node at initial presentation predicted non-recurrence.</p>

Risk Factors for Complicated Influenza A (H1N1) 2009 Disease in Children

<p><b>INTRODUCTION</b>Singapore had its first case of pandemic influenza A (H1N1) 2009 on 26 May 2009. As of 3 August 2009, 440 children with confirmed H1N1were admitted to KK Women's and Children's Hospital (KKH).</p><p><b>MATERIALS AND METHODS</b>This is a retrospective case control study of children admitted from 26 May 2009 to 19 July 2009 with H1N1infection. Cases and controls were first differentiated by whether they were complicated or non-complicated in nature, and subsequently analysed with regards to possible independent risk factors.</p><p><b>RESULTS</b>We analysed 143 admitted children; 48 cases and 95 controls (1: 2 ratio). Significant comorbidity was found in 20.3% (n = 29) of patients with the majority having asthma (n = 18, 12.6 %) followed by obesity (n = 7, 4.9%). Binary logistic regression analysis showed risk factors for complicated disease were comorbidity (adjusted OR 6.0, 95% CI, 2.5 to 14.6, P < 0.0001) and age <2 years (adjusted OR 9.8, 95% CI, 2.4 to 40, P = 0.001). Age less than 5 years was not found to be a risk factor.</p><p><b>CONCLUSION</b>In the early stages of an evolving influenza epidemic when oseltamivir stocks are low, oseltamivir treatment for influenza can be streamlined and offered to those at highest risk who are under 2 years old or have significant comorbidity to prevent complicated disease.</p>

Survey of healthcare workers' attitudes, beliefs and willingness to receive the 2009 pandemic influenza A (H1N1) vaccine and the impact of educational campaigns

<p><b>INTRODUCTION</b>Vaccination against the 2009 pandemic influenza A (H1N1) represents the best method of controlling spread, morbidity and mortality due to the pandemic. While this has been recommended for all healthcare-workers locally, it is unclear if they are willing to accept the vaccination.</p><p><b>MATERIALS AND METHODS</b>A cross-sectional survey was conducted before and after an educational talk on pandemic influenza and vaccines to ascertain responses and stated reasons, as well as identify associated factors.</p><p><b>RESULTS</b>For 235 returned forms prior to the talk, 182 (77.4%) responded positively, while 161 of 192 (83.8%) who returned forms after the talk responded positively. Importantly, 12 of 47 (25.5%) initially negative responses turned positive after education. The desire to protect family, self and patients were the 3 most important reasons for staff wanting to receive the vaccine, while the concern regarding potential side effects was the most important reason for refusal.</p><p><b>CONCLUSIONS</b>A high rate of willingness to receive pandemic influenza vaccine was found, which was in contrast to acceptance rates elsewhere and during previous influenza seasons. Education can play an important role in altering vaccine acceptance behaviour, with an emphasis on addressing concerns with regard to potential side effects.</p>

The efficacy of influenza vaccination in healthcare workers in a tropical setting: a prospective investigator blinded observational study

<p><b>INTRODUCTION</b>Influenza vaccine has been shown to be highly effective in temperate regions with well-defined seasonal influenza. Healthcare workers (HCWs) are advised to receive regular influenza vaccination to protect themselves and their patients. However, there are limited data on the efficacy of influenza vaccine in HCWs in the tropics.</p><p><b>MATERIALS AND METHODS</b>In this observational, investigator blinded cohort study, bi-monthly questionnaires recording influenza-like illness (ILI) episodes and medical leave were administered to 541 HCWs at the Singapore National University Hospital and KK Women's and Children's Hospital from 2004 to 2005. ILI was defined according to a standard symptom score.</p><p><b>RESULTS</b>Baseline characteristics were comparable in both the vaccinated and non-vaccinated groups. Overall, the relative risk of self-reported ILI in vaccinated HCWs was 1.13 [95% confidence interval (CI), 0.98-1.13; P=0.107]; medical leave taken was lower in the vaccinated group [mean 0.26+/-0.6 days per visit, compared with 0.30+/-0.5 days in the non-vaccinated group (P=0.40)]. Because of the reported Northern Hemisphere 2003/04 vaccine mismatch, we stratified the cohort and determined that the group which received a matched vaccine had a relative risk of ILI of 0.49 (95% CI, 0.37-0.66; P<0.001), achieving a vaccine efficacy of 51%. Mean medical leave decreased significantly in HCWs who received the matched vaccine, compared with those who did not receive vaccination (0.13+/-0.3 vs 0.30+/-0.5; P<0.001) and with HCWs vaccinated with mismatched strains (0.13+/-0.3 vs 0.39+/-0.9; P=0.01).</p><p><b>CONCLUSIONS</b>A well-matched influenza vaccine is effective in preventing ILI and reducing sickness absence in healthcare workers in tropical settings. Efforts need to be made to increase influenza vaccination rates and to improve the currently available vaccines.</p>

Skin manifestation of Stenotrophomonas maltophilia infection--a case report and review article

<p><b>INTRODUCTION</b>Stenotrophomonas maltophilia is an aerobic gram-negative bacillus that is a frequent coloniser of fluids used in the hospital setting. It causes infection in immunosuppressed hosts, especially those who are neutropaenic, on chemotherapy and broad spectrum antibiotics. Skin and soft tissue manifestations of Stenotrophomonas maltophilia infection are becoming an increasingly recognised entity; the clinical spectrum ranges from mucocutaneous, skin to soft tissue infections.</p><p><b>MATERIALS AND METHODS</b>We present a case of an 8-year-old girl with acute myeloid leukaemia who developed metastatic skin lesions secondary to Stenotrophomonas maltophilia bacteraemia. The authors reviewed a total of 24 reported cases of mucocutaneous, skin and soft tissue infections by Stenotrophomonas maltophilia. The presentations include metastatic cellulitis, primary cellulitis and infected mucocutaneous ulcers.</p><p><b>RESULTS</b>This is the first locally reported case of metastatic nodular skin lesions caused by Stenotrophomonas maltophilia bacteraemia. This is also the first reported paediatric case of embolic skin lesions caused by Stenotrophomonas maltophilia. Of the 6 cases of Stenotrophomonas maltophilia bacteraemia seen in the paediatric oncology patients from year 2000 to 2004 at our hospital, only 1 case developed metastatic skin lesions.</p><p><b>CONCLUSION</b>Stenotrophomonas maltophilia skin infection should be included into the list of differential diagnoses for metastatic skin lesions in neutropaenic patients, especially with an underlying haematologic malignancy who has received recent chemotherapy and broad spectrum antibiotics. Haematologic malignancy, transplantation, neutropaenic, immunosuppressive therapy and a high severity of illness score were important prognostic factors.</p>